At the present time there is available a wide selection of floatation devices. There is along with this wide selection a wide degree of effectiveness as well as a very wide price range. The most commonly used floatation device comprises simply a billet of a closed cell foam material formed for example from polystyrene foam. Devices of this type do provide adequate floatation, but are not environmentally sound, nor easily repaired if damaged. Some such devices are known to waterlog over time and some are susceptible to chemical attack. Also, the cleaning of algae from the surface is quite difficult, if not impossible.
In an alternative arrangement, rotationally molded plastics hollow shells are used. If these are hollow, a simple puncture will cause a total loss of buoyancy and hence this device is not widely accepted. Foam filled shells of this type are environmentally sound, temperature stable, chemical resistant and structurally sound but are very expensive, and cannot economically compete with the foam billet.